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/*---------------------------------------------------------------------------+

 |  fpu_aux.c                                                                |

 |                                                                           |

 | Code to implement some of the FPU auxiliary instructions.                 |

 |                                                                           |

 | Copyright (C) 1992,1993,1994,1997                                         |

 |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |

 |                  E-mail   billm@suburbia.net                              |

 |                                                                           |

 |                                                                           |

 +---------------------------------------------------------------------------*/

#include "fpu_system.h"

#include "exception.h"

#include "fpu_emu.h"

#include "status_w.h"

#include "control_w.h"

static void fnop(void)

{

}

void fclex(void)

{

  partial_status &= ~(SW_Backward|SW_Summary|SW_Stack_Fault|SW_Precision|

                   SW_Underflow|SW_Overflow|SW_Zero_Div|SW_Denorm_Op|

                   SW_Invalid);

  no_ip_update = 1;

}

/* Needs to be externally visible */

void finit()

{

  control_word = 0x037f;

  partial_status = 0;

  top = 0;            /* We don't keep top in the status word internally. */

  fpu_tag_word = 0xffff;

  /* The behaviour is different from that detailed in

     Section 15.1.6 of the Intel manual */

  operand_address.offset = 0;

  operand_address.selector = 0;

  instruction_address.offset = 0;

  instruction_address.selector = 0;

  instruction_address.opcode = 0;

  no_ip_update = 1;

}

/*

 * These are nops on the i387..

 */

#define feni fnop

#define fdisi fnop

#define fsetpm fnop

static FUNC const finit_table[] = {

  feni, fdisi, fclex, finit,

  fsetpm, FPU_illegal, FPU_illegal, FPU_illegal

};

void finit_()

{

  (finit_table[FPU_rm])();

}

static void fstsw_ax(void)

{

  *(short *) &FPU_EAX = status_word();

  no_ip_update = 1;

}

static FUNC const fstsw_table[] = {

  fstsw_ax, FPU_illegal, FPU_illegal, FPU_illegal,

  FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal

};

void fstsw_()

{

  (fstsw_table[FPU_rm])();

}

static FUNC const fp_nop_table[] = {

  fnop, FPU_illegal, FPU_illegal, FPU_illegal,

  FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal

};

void fp_nop()

{

  (fp_nop_table[FPU_rm])();

}

void fld_i_()

{

  FPU_REG *st_new_ptr;

  int i;

  u_char tag;

  if ( STACK_OVERFLOW )

    { FPU_stack_overflow(); return; }

  /* fld st(i) */

  i = FPU_rm;

  if ( NOT_EMPTY(i) )

    {

      reg_copy(&st(i), st_new_ptr);

      tag = FPU_gettagi(i);

      push();

      FPU_settag0(tag);

    }

  else

    {

      if ( control_word & CW_Invalid )

        {

          /* The masked response */

          FPU_stack_underflow();

        }

      else

        EXCEPTION(EX_StackUnder);

    }

}

void fxch_i()

{

  /* fxch st(i) */

  FPU_REG t;

  int i = FPU_rm;

  FPU_REG *st0_ptr = &st(0), *sti_ptr = &st(i);

  long tag_word = fpu_tag_word;

  int regnr = top & 7, regnri = ((regnr + i) & 7);

  u_char st0_tag = (tag_word >> (regnr*2)) & 3;

  u_char sti_tag = (tag_word >> (regnri*2)) & 3;

  if ( st0_tag == TAG_Empty )

    {

      if ( sti_tag == TAG_Empty )

        {

          FPU_stack_underflow();

          FPU_stack_underflow_i(i);

          return;

        }

      if ( control_word & CW_Invalid )

        {

          /* Masked response */

          FPU_copy_to_reg0(sti_ptr, sti_tag);

        }

      FPU_stack_underflow_i(i);

      return;

    }

  if ( sti_tag == TAG_Empty )

    {

      if ( control_word & CW_Invalid )

        {

          /* Masked response */

          FPU_copy_to_regi(st0_ptr, st0_tag, i);

        }

      FPU_stack_underflow();

      return;

    }

  clear_C1();

  reg_copy(st0_ptr, &t);

  reg_copy(sti_ptr, st0_ptr);

  reg_copy(&t, sti_ptr);

  tag_word &= ~(3 << (regnr*2)) & ~(3 << (regnri*2));

  tag_word |= (sti_tag << (regnr*2)) | (st0_tag << (regnri*2));

  fpu_tag_word = tag_word;

}

void ffree_()

{

  /* ffree st(i) */

  FPU_settagi(FPU_rm, TAG_Empty);

}

void ffreep()

{

  /* ffree st(i) + pop - unofficial code */

  FPU_settagi(FPU_rm, TAG_Empty);

  FPU_pop();

}

void fst_i_()

{

  /* fst st(i) */

  FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);

}

void fstp_i()

{

  /* fstp st(i) */

  FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);

  FPU_pop();

}